Ursa Major

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Ursa major
Image:Ursa major constellation map.png click for larger image
Abbreviation	UMa
Genitive	Ursae Majoris
Symbology	the Great Bear
Right ascension	10.67 h
Declination	55.38°
Area	1280 sq. deg. Ranked 3rd
Number of stars (magnitude < 3)	6
Brightest star	ε UMa (Alioth) (App. magnitude 1.7)
Meteor showers	Alpha Ursa Majorids Leonids-Ursids
Bordering constellations	Draco Camelopardalis Lynx Leo Minor Leo Coma Berenices Canes Venatici Boötes
Visible at latitudes between +90° and −30° Best visible at 21:00 (9 p.m.) during the month of April
Image:Big dipper.triddle.jpg

Ursa Major (Ursa Maior in Latin) is a constellation visible throughout the year in the northern hemisphere. Its name means Great Bear in Latin, and is associated with the legend of Callisto.

1 Names
2 Notable features
3 Notable deep sky objects
4 History
5 Mythology
6 Notable and named stars
7 See also
8 External links

Names

Its seven brightest stars form a famous asterism known in the United Kingdom as the Plough, and was formerly called by the old name Charles' Wain ("wain" meaning "wagon") as it still is in Scandinavia, Karlavagnen.

This common Germanic name originally meant the men's wagon (the churls' wagon) in contrast to the women's wagon (Ursa Minor). There is also a theory that it was named after Charlemagne. In Romania, it is known as Carul Mare ("Great Wagon"), as opposed to Carul Mic ("Small Wagon"), Ursa Minor.

In North America it is commonly known as the Big Dipper, because the major stars can be seen to follow the rough outline of a large ladle, or dipper; this is recognized as a grouping of stars in many cultures throughout the eras.

In Hindu astronomy, it is referred to as (Vrihat) 'Sapta Rishi' meaning "The Seven (Great) Sages".

Notable features

From the bowl to the handle, the stars in the Big Dipper are α (Dubhe), β (Merak), γ (Phecda or Phad), δ (Megrez), ε (Alioth), ζ Mizar, and η (Alkaid or Benetnash), with Bayer designations in consecutive Greek alphabetical order. This assignment of Bayer designations is unusual in that the brightest star in a constellation is normally assigned the letter α. However, Alioth, bearing the ε assignment, is the constellation's brightest star. Mizar has a companion star called Alcor that served as a traditional test of sight. At magnitude about 4.1, Alcor would normally be relatively easy to see with the unaided eye, but its proximity to Mizar renders it more difficult to resolve. Both stars are actually multiple in and of themselves, including the first telescopic and spectroscopic binaries.

Image:Ursamajor-guide.jpg

The star Polaris, the Pole Star, can be found by measuring a line five times the angular distance between the two pointer stars Dubhe and Merak forming the end of the dipper cup, through those stars and up and away from the dipper. The dipper also points the way to other stars, for instance by sweeping down from the handle one reaches Arcturus (α Boötis) and Spica (α Virginis). A mnemonic for this is "Follow the arc to Arcturus, and speed on to Spica."

Except for Dubhe and Alkaid, the stars of the Big Dipper asterism all have proper motions heading towards a common point in Sagittarius. A few other such stars have been identified, and together they are called the Ursa Major Moving Group.

In addition to the Big Dipper, another asterism comes from Arab culture – the "leaps of the gazelle", a series of three pairs of stars:

ν and ξ Ursae Majoris, Alula Borealis and Australis, the "first leap";
λ and μ Ursae Majoris, Tania Borealis and Australis, the "second leap";
ι and κ Ursae Majoris, Talitha Borealis and Australis, the "third leap".

These stars are found along the southwest border of the constellation, the bear's toes.

W Ursae Majoris is the prototype of a class of contact binary variable stars, and ranges in magnitude between 7.75m and 8.48m.

47 Ursae Majoris has a planetary system with three confirmed planets, 2.54 times and 0.76 times the mass of Jupiter.

Notable deep sky objects

Several bright galaxies are found in Ursa Major, including the pair M81 (one of the brightest galaxies in the sky) and M82 above the bear's head, and M101, a beautiful spiral northwest of η Ursae Majoris. Other galaxies in Ursa Major that appear in the Messier catalogue are M108 and M109, both spiral galaxies. All told, the constellation contains about 50 galaxies observable through telescopes available to the amateur astronomer, most of which are below 10th magnitude. The bright planetary nebula M97, also known as the "Owl Nebula" for its appearance in photographs, can be found along the bottom of the bowl of the Big Dipper. Of note as a curiosity more than an interesting deep sky object is M40, a double star that Messier nonetheless included in his catalogue.

History

Image:Ursa Major constellation Hevelius.jpg Ursa Major was one of the 48 constellations listed by Ptolemy. It is one of the most widely-known constellations, having been mentioned by such poets as Homer, Spenser, Shakespeare, and Tennyson. The Finnish epic Kalevala mentions them, and Vincent Van Gogh painted them in his Starry Night Over the Rhone.

When slavery was still practised in the southern part of the United States of America, slaves wishing to escape to the Yankee North were advised to "follow the drinking gourd"— the circumpolar Big Dipper— towards freedom.

Mythology

The constellation of Ursa Major has been seen by many distinct civilizations as a bear. In consequence, together with the nearby Ursa Minor, it formed the basis of the myth of Callisto.

In earlier times, Greek mythology did not consider Ursa Major a bear, and instead its 3 bright stars (situated in the tail) were seen as apples growing on a tree (sometimes represented by the fainter stars in the remainder of the constellation). At the same time, the stars of Ursa Minor were associated with the Hesperides. These two groups of stars, together with Libra, Boötes and Draco, may have inspired the myth of the apples of the Hesperides, one of The Twelve Labours of Hercules.

Notable and named stars

BD	F	Names and other designations	Mag.	Dist. ly	Comments
ε	77	Epsilon Ursae Majoris, Alioth, Aliath	1.76	80.9	< (?) a corruption of al-jawn "the black horse", originally applied to Mizar of Mizar and Alcor, the "horse and rider" Alpha2 Canum Venaticorum type variable star
α	50	Alpha Ursae Majoris, Dubhe, Dubh, Dubb, Thahr al Dub al Akbar, Ak	1.81	124	< ظهر الدب الأكبر z̧ahr ad-dubb al-akbar Back of the greater bear
η	85	Eta Ursae Majoris, Benetnasch, Alkaid, Elkeid	1.86	101	< القائد البنات النعش al-qāid al-banāt an-na^c "The leader of the daughters of the bier" (the daughters of the bier, i.e. the mourning maidens, are the three stars of the handle of the Big Dipper, Alkaid, Mizar, and Alioth.)
ζ	79	Mizar, Zeta Ursae Majoris, Mizat, Mirza	2.23	78.2	< مئزر mi´zar girdle visual double star with Alcor
β	48	Beta Ursae Majoris, Merak, Mirak	2.34	79.4	< ? al-maraqq The loins (flank?) [of the bear]
γ	64	Gamma Ursae Majoris, Phad, Phecda, Phegda, Phekha, Phacd	2.41	83.7	< الفخذ الدب al-faxð al-dubb The thigh of the bear
ψ	52	Psi Ursae Majoris	3.00	147
μ	34	Mu Ursae Majoris, Tania Australis, Alkafzah Australis	3.06	249	< القفزة الثانية al-qafzat aθ-θāniyah (or at-tāniyah) The second leap (of the gazelle) [القفزة by itself is al-qafzah] + austrālis southern Semiregular variable
ι	9	Iota Ursae Majoris, Talitha Borealis, Talita Borealis, Dnoces, Alphikra Borealis	3.12	47.7	< القفزة الثالثة al-qafzat aθ-θāliθah (or at-tālitah) The third leap (of the gazelle) + boreālis northern < second backwards < الفقرة الثالثة al-fiqra[h] The vertebra Double binary star.
θ	25	Theta Ursae Majoris, Al Haud, Sarir, Sarir Bonet?	3.17	44.0	< الحوض al-ħawđ̧ The pond/pelvis (which?) < سرير as-sarīr The couch/bed [of the dead]
δ	69	Delta Ursae Majoris, Megrez, Kaffa	3.32	81.4	< المغرز al-maghriz The root/insertion-point [of the bear's tail]
ο	1	Omicron Ursae Majoris, Muscida	3.35	184	< post-classical Latin musus "snout", "muzzle" Muscida shared with π¹^,² Ursae Majoris
λ	33	Lambda Ursae Majoris, Tania Borealis, Alkafzah Borealis	3.45	134	< القفزة الثانية al-qafzat aθ-θāniyah (or at-tāniyah) The second leap (of the gazelle) [القفزة by itself is al-qafzah] + boreālis northern
ν	54	Nu Ursae Majoris, Alula Borealis	3.49	421	< القفزة الأولى al-qafzat al-´ūla´ The first leap (of the gazelle) + boreālis northern
κ	12	Kappa Ursae Majoris, Talitha Australis, Al Kaprah, Alphikra Australis	3.57	423	< القفزة الثالثة al-qafzat aθ-θāliθah The third leap (of the gazelle) + austrālis southern Al Kaprah is a corruption of القفزة al-qafzah The leap < الفقرة الثالثة al-fiqra[h] The vertebra
h	23	23 Ursae Majoris	3.65	75.5
χ	63	Chi Ursae Majoris, Alkafzah, Alkaphrah, El Koprah	3.69	196	< القفزة al-qafzah The leap
υ	29	Upsilon Ursae Majoris	3.78	115	Delta Scuti type variable star
ξ	53	Xi Ursae Majoris, Alula Australis	3.79	28.8	< القفزة الأولى al-qafzat al-´ūla´ The first leap (of the gazelle) + austrālis southern binary star; component magnitudes: 4.4 + 4.9 RS Canum Venaticorum type variable star
g	80	Alcor, 80 Ursae Majoris, Saidak	3.99	81.2	< (?) a corruption of al-jawn "the black horse", originally applied to Mizar. Alcor is the rider of the "horse and rider" visual double star with Mizar
f	15	15 Ursae Majoris	4.46
	26	26 Ursae Majoris	4.47
d	24	24 Ursae Majoris	4.54
π²	4	Pi-2 Ursae Majoris, Muscida	4.59	252	< post-classical Latin musus "snout", "muzzle" Muscida shared with ο Ursae Majoris
	83	83 Ursae Majoris	4.63
ω	45	Omega Ursae Majoris	4.66	267
τ	14	Tau Ursae Majoris	4.67	122
ρ	8	Rho Ursae Majoris	4.74	287
	55	55 Ursae Majoris	4.76
σ²	13	Sigma-2 Ursae Majoris	4.80	66.7
e	18	18 Ursae Majoris	4.80
	36	36 Ursae Majoris	4.82
	78	78 Ursae Majoris	4.93
	56	56 Ursae Majoris	4.99
	46	46 Ursae Majoris	5.02
	47	47 Ursae Majoris	5.03	45.9	has two planets
	49	49 Ursae Majoris	5.06
	38	38 Ursae Majoris	5.12
	44	44 Ursae Majoris	5.12
σ¹	11	Sigma-1 Ursae Majoris	5.15	500
	27	27 Ursae Majoris	5.15
	37	37 Ursae Majoris	5.16
c	16	16 Ursae Majoris	5.18
	67	67 Ursae Majoris	5.22
	31	31 Ursae Majoris	5.27
	17	17 Ursae Majoris	5.28
	57	57 Ursae Majoris	5.30
	61	61 Ursae Majoris	5.31
	74	74 Ursae Majoris	5.37
	82	82 Ursae Majoris	5.46
A	2	2 Ursae Majoris	5.47
	70	70 Ursae Majoris	5.54
	59	59 Ursae Majoris	5.56
	6	6 Ursae Majoris	5.57
	42	42 Ursae Majoris	5.57
	81	81 Ursae Majoris	5.60
π¹	3	Pi-1 Ursae Majoris, Muscida	5.64	46.5	< post-classical Latin musus "snout", "muzzle" Muscida shared with ο Ursae Majoris BY Draconis type variable star
	43	43 Ursae Majoris	5.66
	73	73 Ursae Majoris	5.68
	84	84 Ursae Majoris	5.68
	86	86 Ursae Majoris	5.70
b	5	5 Ursae Majoris	5.72
	62	62 Ursae Majoris	5.73
	32	32 Ursae Majoris	5.74
	22	22 Ursae Majoris	5.77
	39	39 Ursae Majoris	5.79
	71	71 Ursae Majoris	5.82
	66	66 Ursae Majoris	5.83
	58	58 Ursae Majoris	5.94
	51	51 Ursae Majoris	6.01
	76	76 Ursae Majoris	6.02
	75	75 Ursae Majoris	6.07
	60	60 Ursae Majoris	6.09
	35	35 Ursae Majoris	6.32
	41	41 Ursae Majoris	6.34
	68	68 Ursae Majoris	6.34
		Groombridge 1830	6.42	29.9	nearby yellow subdwarf
	28	28 Ursae Majoris	6.51
	65	65 Ursae Majoris	6.54		binary star; component magnitudes: 6.54, 7.16
	71	71 Ursae Majoris	7.09
	40	40 Ursae Majoris	7.22
		Lalande 21185	7.48	8.2	nearby, has possible planets
		W Ursae Majoris	7.75v	162	variable star: 7.75–8.48
		Winnecke 4, M40	9.0	510	double star; component magnitudes: 9.0, 9.3
		SZ Ursae Majoris	9.31v		variable star
		CF Ursae Majoris	12.00v		variable star
		WX Ursae Majoris	14.4v		variable star